README

TailFromSentinel
Parses a file, looking for a sentinel line that satisfies a block, and returns
all lines from there until the end of the file (including the sentinel itself).
This can be handy when you are looking for information in a log file only after
a certain condition (eg. a date) has been met.
You can either use it on it's own, or subclass it to build your own custom
tail-like classes.
Standalone:
File.open('/var/log/messages', 'r') do |file|
tfs=TailFromSentinel::Base.new(file) { |line| line =~ /Dec 20 11:2\d+/ }
end
tfs.data # => [ 'Dec 20 11:20:00 ...', 'Dec 20 11:21:00 ...', ... ]
Subclassed:
class TailMyFile < TailFromSentinel::Base
DATA_ROOT="/path/to/data/"
def initialize(data_file)
file=File.open(File.join(DATA_ROOT, data_file), 'r') do |file|
super(file, &select_sentinel_criteria(data_file))
end
end
def select_sentinel_criteria(data_file)
case data_file
when ''production.log'
Proc.new { |line| line =~ /pattern/ }
when 'development.log'
Proc.new { |line| line =~ /another pattern/ }
else
raise "Unhandled file: #{data_file}"
end
end
end
t=TailMyFile.new('production.log')
t.data # => [ 'Started GET "/pattern ...", " Processing ... ", ... ]